Tuesday, 22 January 2013

How to repair a 316 stainless steel engine wet exhaust trap

This has been a project waiting for a start, the custom made 316 exhaust trap had a weld problem from the day it was first used, a small pin hole leak which was welded closed.

That was on the lower plate and that circular plate has weeped a little ever since.

Recently I have noticed clean sea water in a boats bilge after its Perkins 4108 diesel engine has been run, this was probably from the water trap, removal and an inspection followed by an epoxy repair was the only way to fix this.

Note, a carbon monoxide alarm is just above the exhaust box, it has never even chirped, then again I note no smell of exhaust fumes at all, tested the alarm indicates its working.

Click on the pictures to enlarge.

Some serious degrade of so called stainless steel has taken place here. The cost to have a new one made will be large, watch how its repaired using our epoxies.

After cleaning the parts were bead blasted clean, the damage soon became a lot clearer then.

check the loss of metal!

Nice and clean but see that small hole on the right.

I used JB Weld epoxy to fill most holes but 816 epoxy and micro balloons would also work.

Nice and clean, I used the bottom of a plastic container to hold an epoxy mix with some biaxial glass gloss around the bottom, when the epoxy was cured the pink plastic was cut away.

The stainless tube was glassed with biaxial and epoxy 3/4s of the way up the tube, we now have a composite exhaust box, the insides of the elbows were also given a clean coat of epoxy to save the metal for another decade or more.

Refitted, the engine was then run until it was nice and warm, then when switched off, the stainless hose clams were re tightened just to be sure there are no leaks.

This is a simple repair, its really low cost but does take time while the epoxy cures, the coatings have now been painted with International Paints Intergard epoxy primer and Interthane 990 top coat paints.